This invention relates to hydraulically operable rock drills of a type having a power piston adapted to carry a drill string.
A rock drill is disclosed in my co-pending companion applications--Ser. No. 468,899, filed May 10, 1974 for An Hydraulic Tool, and Ser. No. 479,208, filed June 14, 1974 for An Hydraulic Rock Drill Tool having Automatic Carriage Feed--wherein the housing of the tool defines a bulk oil accumulator about a power piston to provide a proximity source of pressurized oil to reciprocate the piston which is designed to carry a work implement, such as a drill string and attached rock bit; wherein a rotation motor operating independently of the piston functions to rotate the piston without interfering with the reciprocating action of the latter; wherein a valve controlling feed of pressurized oil from the accumulator to reciprocate the piston is powered by a motor operating continuously from oil also flowing to it from the accumulator; and wherein a carriage carrying the tool is hydraulically movable along a guide channel to feed the tool relative to the work concurrently with the reciprocating action of the piston.
The present invention represents a variation from the structure set forth in my aforementioned companion applications, particularly in that it eliminates the motor for effecting operation of the control valve, and provides other hydraulically operable means to this end; in that it provides a distinctly different mode of operation for effecting automatic hydraulic feed of the carriage mounted tool along the guide channel; and in that it includes snubber means for absorbing shocks in the event of an overriding action of the piston.
In accordance with the present invention, there is provided an hydraulic rock drill comprising a housing; a piston cylinder in the housing; a floating piston hydraulically reciprocable in the cylinder having a piston rod adapted externally of the housing for attachment of a drill string thereto; a bulk oil reservoir in the housing surrounding the cylinder providing a proximity source of constantly pressurized oil for reciprocating the piston; control valve means in the housing for causing effective application of pressurized oil from the reservoir alternately to opposite ends of the piston to reciprocate the latter; hydraulically operable plunger means for actuating the control valve means; means determining the operation of the plunger means as a consequence of reciprocating action of the piston; snubber means disposed in the cylinder in the forward path of the piston for damping overriding forward movement of the piston on a work stroke; a rotation motor mounted to the housing having a drive shaft in axial alignment with the piston; a slidable spline connection between the piston and the drive shaft allowing concurrently transmission of rotation of the drive shaft to the piston and axial movement of the piston relative to the drive shaft; carriage means mounting the housing for movement along a guide channel relative to a work objective; and hydraulically operable carriage feed means connected with the carriage effective following a predetermined extent of movement of the piston relative to the cylinder on a work stroke to move the carriage together with the housing forwardly along the guide channel.